Background: Interdisciplinary trauma teams perform critical patient resuscitations under highly dynamic, time- pressured situations. As a result, they are particularly susceptible to safety threats resulting from poor teamwork. Several studies demonstrate that trauma team leaders perform a pivotal role and therefore may be an important leverage point for improving patient safety. Simulation-based training has been proposed as an effective method to improve team leadership; however, no studies have systematically assessed the effectiveness of simulation-based leadership training at the patient level. Objective: The overall objective of the proposed project is to evaluate the impact of simulation-based team leadership training on patient care during trauma resuscitations. The work is organized into three aims: (1) develop and assess the content validity of comprehensive trauma team leadership measures, (2) assess the impact of simulation-based team leadership training on leadership, teamwork, and patient care during trauma resuscitations, and (3) determine the feasibility of assessing the effect of simulation-based leadership training on patient outcomes. Methods: This project uses a randomized controlled design to evaluate the impact of simulation-based leadership training on patient care during trauma resuscitations. Briefly, 70 second- and third-year resident trauma team leaders will be randomized to either training (intervention) or no training (control) conditions. Those in the intervention group will receive a 6-hour team simulation-based leadership curriculum. Primary outcomes for training effectiveness will be (a) team leadership behavior, (b) teamwork behaviors, and (c) patient care during actual trauma resuscitations. Secondary outcomes include the feasibility of assessing patient outcomes (e.g., mortality, adverse events, length of stay). Multivariate linear regression analysis will be used to examine the effects of training on primary outcomes. Implications and Impact: This study will advance the patient safety mission of AHRQ by systematically evaluating simulation-based training outcomes at the individual (leader), team, and patient levels. The proposed project brings together experts in team and simulation science, resuscitation outcomes, and patient safety. The findings will be widely applicable to healthcare teams from multiple disciplines and will fill an important gap in simulation-based research.